<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>逼真的雪花飘落特效</title>

<style type="text/css">
body {
	background-color:#000044;
	background:url(images/timg.jpg)  no-repeat;
    background-size: cover;
	margin:0px;
	overflow:hidden;
}
a {
	color:#0078ff;
}
</style>

</head>
<body onLoad="init()">

<script type="text/javascript" src="js/ThreeCanvas.js"></script>
<script type="text/javascript" src="js/Snow.js"></script>
<script type="text/javascript">
var SCREEN_WIDTH = window.innerWidth;
var SCREEN_HEIGHT = window.innerHeight;

var container;

var particle;

var camera;
var scene;
var renderer;

var mouseX = 0;
var mouseY = 0;

var windowHalfX = window.innerWidth / 2;
var windowHalfY = window.innerHeight / 2;

var particles = []; 
var particleImage = new Image();//THREE.ImageUtils.loadTexture( "img/ParticleSmoke.png" );
particleImage.src = 'images/ParticleSmoke.png'; 



function init() {

	container = document.createElement('div');
	document.body.appendChild(container);

	camera = new THREE.PerspectiveCamera( 75, SCREEN_WIDTH / SCREEN_HEIGHT, 1, 10000 );
	camera.position.z = 1000;

	scene = new THREE.Scene();
	scene.add(camera);
		
	renderer = new THREE.CanvasRenderer();
	renderer.setSize(SCREEN_WIDTH, SCREEN_HEIGHT);
	var material = new THREE.ParticleBasicMaterial( { map: new THREE.Texture(particleImage) } );
		
	for (var i = 0; i < 500; i++) {

		particle = new Particle3D( material);
		particle.position.x = Math.random() * 2000 - 1000;
		particle.position.y = Math.random() * 2000 - 1000;
		particle.position.z = Math.random() * 2000 - 1000;
		particle.scale.x = particle.scale.y =  1;
		scene.add( particle );
		
		particles.push(particle); 
	}

	container.appendChild( renderer.domElement );


	document.addEventListener( 'mousemove', onDocumentMouseMove, false );
	document.addEventListener( 'touchstart', onDocumentTouchStart, false );
	document.addEventListener( 'touchmove', onDocumentTouchMove, false );
	
	setInterval( loop, 1000 / 60 );
	
}

function onDocumentMouseMove( event ) {

	mouseX = event.clientX - windowHalfX;
	mouseY = event.clientY - windowHalfY;
}

function onDocumentTouchStart( event ) {

	if ( event.touches.length == 1 ) {

		event.preventDefault();

		mouseX = event.touches[ 0 ].pageX - windowHalfX;
		mouseY = event.touches[ 0 ].pageY - windowHalfY;
	}
}

function onDocumentTouchMove( event ) {

	if ( event.touches.length == 1 ) {

		event.preventDefault();

		mouseX = event.touches[ 0 ].pageX - windowHalfX;
		mouseY = event.touches[ 0 ].pageY - windowHalfY;
	}
}

//

function loop() {

for(var i = 0; i<particles.length; i++)
	{

		var particle = particles[i]; 
		particle.updatePhysics(); 

		with(particle.position)
		{
			if(y<-1000) y+=2000; 
			if(x>1000) x-=2000; 
			else if(x<-1000) x+=2000; 
			if(z>1000) z-=2000; 
			else if(z<-1000) z+=2000; 
		}				
	}

	camera.position.x += ( mouseX - camera.position.x ) * 0.05;
	camera.position.y += ( - mouseY - camera.position.y ) * 0.05;
	camera.lookAt(scene.position); 

	renderer.render( scene, camera );

	
}
</script>

</body>
</html>